Encyclopedia of

Rigor Mortis and Other Postmortem Changes

Once the heart stops beating, blood collects in the most dependent parts
of the body (livor mortis), the body stiffens (rigor mortis), and the body
begins to cool (algor mortis).

The blood begins to settle in the parts of the body that are the closest
to the ground, usually the buttocks and back when a corpse is supine. The
skin, normally pink-colored because of the oxygen-laden blood in the
capillaries, becomes pale as the blood drains into the larger veins.
Within minutes to hours after death, the skin is discolored by livor
mortis, or what embalmers call "postmortem stain," the
purple-red discoloration from blood accumulating in the lowermost
(dependent) blood vessels. Immediately after death, the blood is
"unfixed" and will move to other body parts if the
body's position is changed. After a few hours, the pooled blood
becomes "fixed" and will not move. Pressing on an area of
discoloration can determine this; if it blanches (turns white) easily,
then the blood remains unfixed. Livor mortis is usually most pronounced
eight to twelve hours after death. The skin, no longer under muscular
control, succumbs to gravity, forming new shapes and accentuating
prominent bones still further. The body then begins to cool.

At the moment of death, the muscles relax completely—a condition
called "primary flaccidity." The muscles then stiffen,
perhaps due to coagulation of muscle proteins or a shift in the
muscle's energy containers (ATP-ADP), into a condition known as
rigor mortis. All of the body's muscles are affected. Rigor mortis
begins within two to six hours of death, starting with the eyelids, neck,
and jaw. This
sequence may be due to the difference in lactic acid levels among
different muscles, which corresponds to the difference in glycogen levels
and to the different types of muscle fibers. Over the next four to six
hours, rigor mortis spreads to the other muscles, including those in the
internal organs such as the heart. The onset of rigor mortis is more rapid
if the environment is cold and if the decedent had performed hard physical
work just before death. Its onset also varies with the individual's
age, sex, physical condition, and muscular build.

After being in this rigid condition for twenty-four to eighty-four hours,
the muscles relax and secondary laxity (flaccidity) develops, usually in
the same order as it began (see Table 1). The length of time rigor mortis
lasts depends on multiple factors, particularly the ambient temperature.
The degree of rigor mortis can be determined by checking both the finger
joints and the larger joints and ranking their degree of stiffness on a
one- to three- or four-point scale. Many infant and child corpses will not
exhibit perceptible rigor mortis. This decreased perceptible stiffness may
be due to their smaller muscle mass.

During this period, the body gradually cools in a process called algor
mortis. The best way to accurately assess a corpse's temperature is
with a core (tympanic membrane, liver, or rectal) thermometer. Rectal
insertion may be difficult and cause postmortem injury.

A few adult corpses may not undergo perceptible rigor mortis. Folklore in
Britain, the Philippines, and elsewhere ascribed fearsome supernatural
powers to these "limber corpses."

In the early nineteenth century, the American and British poor often
prepared their own dead for burial in a process called
"laying-out," "streeking," or rendering the
"last offices." Women normally washed the corpse, plugged
its orifices, closed its eyes and mouth, straightened its limbs, and
dressed or shrouded it. It was ritually important to close the eyes
quickly, being that they are the first to rigidify in rigor mortis, and it
was thought that a corpse with open eyes posed a threat to its kin. As has
long been the case in many cultures, they used coins to keep the
corpse's eyes closed. The practice of using coins endures,
representing a feeling that money, so important in life, may also be
important in death.

TABLE 1

Approximate times for algor and rigor mortis in temperate regions

Body temperature

Body stiffness

Time since death

warm

not stiff

dead not more than three hours

warm

stiff

dead 3 to 8 hours

cold

stiff

dead 8 to 36 hours

cold

not stiff

dead more than 36 hours

SOURCE:
Stærkeby, M. "What Happens after Death?" In the
University of Oslo Forensic Entomology [web site]. Available from
http://folk.uio.no/mostarke/forens_ent/afterdeath.shtml.

In the embalming process, embalmers first position the body. They then
relieve rigor mortis by flexing, bending, and massaging the arms and legs.
They then move the limbs to a suitable position, usually with legs
extended and arms at the sides or hanging over the sides of the table, so
that blood can drain into and expand the vessels for better embalming.
They need to position the body before injecting embalming fluid, for no
matter what stage of rigor mortis a body is in, once embalming fluid is
injected, the muscles begin to firm up, or "set." (Without
embalming, they would become flaccid over a period of hours.) After
embalming, the muscles harden gradually over the next eight to twelve
hours. Once they are set, embalmers cannot alter the body's
position.

Putrefaction

In the absence of embalming or relatively rapid cremation, the body
putrefies. The first sign of putrefaction is a greenish skin discoloration
appearing on the right lower abdomen about the second or third day after
death. This coloration then spreads over the abdomen, chest, and upper
thighs and is usually accompanied by a putrid odor. Sulphur-containing
intestinal gas and a breakdown product of red blood cells produce both the
color and smell. The ancient Greeks and the Etruscans paid homage to this
well-recognized stage of decomposition by coloring a prominent god
aqua-marine, considered the color of rotting flesh.

Bacteria normally residing in the body, especially the colon, play an
important part in digestion of food during life. They also contribute
mightily to
decomposition after death—the process of putrefaction. The smell,
rather than the sight, is the most distinctive thing about a putrefying
body.

Under normal conditions, the intestinal bacteria in a corpse produce large
amounts of foul-smelling gas that flows into the blood vessels and
tissues. It is this gas that bloats the body, turns the skin from green to
purple to black, makes the tongue and eyes protrude, and often pushes the
intestines out through the vagina and rectum. The gas also causes large
amounts of foul-smelling bloodstained fluid to exude from the nose, mouth,
and other body orifices. Two of the chemicals produced during putrefaction
are aptly named putrescine (1,4-diaminobutane) and cadaverine
(1,5-pentanediamine). If a person dies from an overwhelming bacterial
infection, marked changes from putrefaction can occur within as few as
nine to twelve hours after death.

By seven days after death, most of the body is discolored and giant
blood-tinged blisters begin to appear. The skin loosens and any pressure
causes the top layer to come off in large sheets (skin slip). As the
internal organs and the fatty tissues decay, they produce large quantities
of foul-smelling gas. By the second week after death, the abdomen,
scrotum, breasts, and tongue swell; the eyes bulge out. A bloody fluid
seeps out of the mouth and nose. After three to four weeks, the hair,
nails, and teeth loosen and the grossly swollen internal organs begin to
rupture and eventually liquefy. The internal organs decompose at different
rates, with the resistant uterus and prostate often intact after twelve
months, giving pathologists one way to determine an unidentified
corpse's sex.

Aside from the action of microbes, the breakdown of cells (autolysis)
helps destroy the body unless the corpse is kept at or below 32 degrees
Fahrenheit. Cells die (necrosis) through the progressive destruction of
their various parts. First, the cellular fluid (cytoplasm) and the
energy-releasing mechanism (mitochondria) swell. Various products,
including calcium, begin to coalesce in the mitochondria as other
mechanisms within the cell dissolve. Next, loss of energy causes the cell
to lose its connections with neighboring cells (tissue destruction) and to
further lose control over the fluid within its outer barrier, much like an
over-filled water balloon. The cell controller (nucleus) fails, and the
packs of destructive acids (enzymes) within the cell break loose. These
enzymes complete the work of destroying the cell.

The sociologist Ruth Richardson summed up decomposition aptly: "The
physicality of a human corpse is undeniable. It is a carcass, with a
predisposition to decay, to become noisome, obnoxious to the senses, and
harrowing to the emotions. Disposal of such perishable remains is
imperative" (1987, p. 15).

User Contributions:

oh my gosh, i was afraid of death before this article, and now even more so, i'm 62. is there not a way just befor death that a person could jump or be dumped into somethng like a volcano and be done with it. yuk. sorry but my fingers are cold when writing this, i think i'll drive down to italy and look into mt etna, no joke, i can't imagain my body going through such an awful process. i've taken such care of it, i know we all must die, but at death it would be nice to be a flash of dust. thank you anyway for the article.
marie

Thank you so much for your article. I am not scared of dying but dont want to linger on breathless and in pain. My friends husband, when still alive with cancer, had a load of fluid gradually seeping out of his feet and then up his legs. Was he decomposing even though he was still alive? An answer would be appreciated. Also I would love to work in an undertakers on a voluntary basis, anyone got any suggestions as to how I may do this.

im a medical student from indonesia, well, i realy interest with medicolegal, i want ask u a question, what happened in a biocululair in rigor mortis proccess? thanks before....im sory if my english is too bad

when does the brain decompose? If a body decomposes in the open environment rain then extreme heat (3 1/2 months)why would the brain be the only thing not gone and why would it have a carmelized/glossy look to the skeleton why woul the ears be gone but not the nose?

Recently viewed a relative's body at the funeral home. The arms and hands were not in the usual crossed position but arms down and hand curled as if they were holding something. Very unnatural. The rest of the body was lying flat. What would cause this?

when we found my grandmother had passed away at home she was very stiff at 12:30 that afternoon. we found her deceased on january 1st. oven was on in kitchen but kitchen was room temperature. did death occur that day or day before on december 31st.

My son died on 5.22.2014. He was last seen by his roommate at 11pm. The EMT was there at 6:50am and full rigormortis has set in. They could not open his mouth or hands for photos. It was 72 degrees in his apt. and he was about 5'7 weighed 190lbs. He was considered obese. Were these conditions, his weight and the time within the limits of the timeframe for full rigormortis?

Dear Laura,
I was moved by the story of your tragic loss, and hope that you find the peace you are looking for.
Though I recognise your need for answers, I believe that visiting sites such as this can only prolong your grief.
The fact of your Son's death is quite enough for you to cope with, and it may be that remembering the happy times will help you to manage your obvious anguish.
Kind Regards,
Stephen,
Lancashire,
England.